喷水冷却火灾后方钢管混凝土界面黏结性能试验研究

EXPERIMENTAL STUDY ON BONDING PROPERTIES OF CONCRETE FILLED SQUARE STEEL TUBES AFTER FIRE SPRINKLER COOLING

为揭示消防喷水冷却火灾后方钢管与核心混凝土界面间的黏结滑移性能,设计制作了23个方钢管混凝土试件,试件考虑了历经最高温度、混凝土的黏结长度、混凝土强度、冷却方式等变化参数。通过黏结滑移推出试验研究,观察了各试件的破坏形态,获取了荷载-滑移全过程曲线及特征点参数,分析了不同参数对界面黏结强度的影响并提出了计算表达式、构建了荷载-滑移本构关系模型。研究表明:加载端与自由端的荷载-滑移曲线形状相似,自由端较晚滑移;随着火灾温度的升高,界面间黏结强度均表现为先增后减的变化趋势,且火灾温度为600℃时达到峰值;随着火灾温度的升高,黏结长度对界面黏结强度影响显著且呈反比关系;消防喷水冷却后试件界面黏结强度较自然冷却低,下降幅度随着温度的升高逐渐增大。

In order to reveal the bond-slip behavior between steel tube and core concrete after fire sprinkler cooling,23 concrete-filled square steel tube(CFSST)specimens were designed and manufactured,and the variation parameters included the maximum temperature,the anchorage length of concrete,the concrete strength and the cooling mode.Through the push-out test,the failure modes of the specimens were observed,the whole load-slip curve and characteristic parameters were obtained,the influence of different parameters on the bond strength of the interface was analyzed,the calculation formula was put forward and the load-slip constitutive relationship model was constructed.The results showed that the shape of load-slip curve at the loading end was similar to that at the free end,and the free end sliped later.With the increase of maximum temperature,the interfacial bond strength increased first and then decreased,and reached its peak at 600℃.At the same time,the anchorage length had a significant effect on the interfacial bond strength and the relationship between them was inverse.The interfacial bond strength of the specimens cooled by fire sprinkler was lower than that of the natural cooling specimens.The decreasing range was gradually increased with the increase of temperature.